"We're constantly looking for new techniques, new ways to maximize forage intake," says John Noble, general manager at Southview Dairy in Castile, N.Y. "Doing so helps us maximize cow health, which, in turn, leads to higher milk production."

Dairy producer John Noble, left and Bob Kozlowski, nutritionist with western New York Agway, examine a silage sample at Southview Dairy in Castle, N.Y.

It was with that goal in mind that Bob Kozlowski, nutritionist with western New York Agway, encouraged Southview Dairy to give fermentation analysis a try. The 3,000-cow dairy had been experiencing a displaced abomasum rate of 10 percent to 12 percent. Incidence of ketosis was higher than normal and milk production starts were less than ideal for newly-fresh cows. A fermentation analysis revealed a high butyric acid level in the haylage -- most likely because the forages had been ensiled too wet. Mindful of the problem, the farm was careful the next year to put up haylage that was 5 percentage points drier and corn silage that was 3 percentage points drier. And, the cows responded. The displaced abomasum rate among newly-fresh cows fell to a respectable 3 percent to 5 percent, the incidence of ketosis dropped dramatically and fresh cow starts increased by 8 to 10 pounds per cow per day.

You, too, can make better feeding decisions and improve silage production by using fermentation analysis to determine the acid profile of your silages.

Focus on the Details
Most everyone has experienced frustration when feeding silage. The silage looked good, the wet chemistry analysis said it had good nutritional value, but the cows didn't really go for the feed and produced less milk than expected.

Now you can pinpoint the problem. Fermentation analysis reveals which acids were produced, and in what quantities, during fermentation.

The acid profile -- lactic, acetic, butyric and propionic -- affects the palatability and stability of the silage and can be a major influence on the rumen health of your cows, explains Kozlowski. Small changes in the percentage of some of these acids -- by just 1 or 2 percent -- can seriously alter your cows' acceptance of the forage and reduce milk production. And, since changes in the acids tend to coincide with changes in packing or dry matter content at harvest, you can use fermentation analysis to help you improve next year's silage production.

Until recently, people relied on wet chemistry or NIR as standard measures of forage quality. And, while those tests do measure nutritional values such as dry matter, protein, NDF, ADF, NEL and calculate a relative feed value, they do not measure palatability or stability of the feed, explains Bob Corbett, veterinarian and nutritionist from Spring City, Utah.

Dairy producers who want to maximize dry matter intake and push milk production higher need to pay attention to more than just protein and energy. They need to focus on acid levels, too, because they can have a huge impact on palatability and stability.

 

A Comparison Of Haylage Samples

The chart above shows the lactic acid content obtained from a fermentation analysis test for 16 haylage samples. The red line shows the dry matter content of each sample, while the blue shows the lactic acid content as a percent of the total acid profile. The target lactic acid percent for haylage is about 70%.

The chart above shows how the pH (blue line) changes with the dry matter content (red line) for 16 different haylage samples. The target pH  after fermentation for haylage is 4.3 to 4.5 for alfalfa haylage and 4.3 to 4.7 for grass haylage.

Making the Most of Palatable Feeds
Fermentation analysis can help you place the most appealing, palatable feed in front of your cows.

That is especially important for close-up cows. For example, butyric acid -- even a small amount -- can cause a close-up cow to refuse her feed. Butyric acid has a rotten or rancid smell, and it only takes a small amount in the silage to cause problems. At low levels of butyric acid -- just 1 percent -- the silage may not smell when you mix it, but if you bring a handful up to your nose, you'd probably notice it. (For more on understanding the different smells associated with silage and acid production, see the table below "Use Your Nose." ) 

Use Your Nose
"Each of the different acids produced in silage and haylage during fermentation has a distinctive smell", says Kurt Rupel, dairy specialist with Pioneer Hi-Bred International. Rupel, who trains Pioneer sales representatives on silage management, says producers can train their noses over time to detect these sometimes subtle smells.
Acid	Smell or Sensation
Butyric acid	Rotten
Lactic acid	Clean, sweet
Acetic acid	Like vinegar
Propionic acid	You'll feel a sting in the back of your nose

Knowing the acid profile of silages is an even more precise way to select forages for your close-up cows.

When haylage is harvested too wet, with a dry matter content of less than 35 percent, clostridial fermentation can occur. This can result in high levels of butyric acid, ammonia and a high pH, which often leads to unpalatable forage, says Dan Kluth, dairy nutritionist for Standard Nutrition in Jerome, Idaho.

For example, in one herd that Kluth works with, milk production dropped from about 84 pounds per day to about 70 to 75 pounds per day when a new bag of haylage was opened. An analysis of the haylage revealed a low lactic acid content. So, Kluth cut the amount of haylage fed by half, added enough dry hay to compensate, and also added 2.5 pounds of molasses to help offset the low lactic acid levels with added sugars. Production rebounded to 80 pounds per day. Although he didn't gain back 100 percent of lost production, Kluth did find a way to feed less-than-optimal haylage, while limiting financial loss.

In addition to palatability problems, knowing the acid profile of silage can help you manage health problems, too, says Kozlowski. For example, butyric acid and reduced dry matter intake may have a direct correlation to the production of ketone bodies, which, when produced in excess, can lead to ketosis. High ammonia concentrations of wet forages also can reduce palatability and dry matter intake. So, to help keep cows healthy during the stress surrounding calving, you'll want to feed forages with no butyric acid and low ammonia levels.

Halyage Test Results At Southview Dairy
	1997 1st Cutting	1998 1st Cutting
Dry Matter	29.3%	35.6%
pH	4.95%	4.54%
Lactic Acid	4.9%	6.8%
Acetic Acid	6.94%	2.56%
Propionic Acid	0.14%	0.16%
Iso-butyric	0.01%	0.09%
Butyric Acid	0.51%	0.01%
Total VFAs	12.49%	9.60%
Lactic Acid/VFA	39.23%	70.69%
A small change in the dry matter content of haylage at harvest resulted in a big change in the acid profile.
Source: Bob Kozlowski, Western New York Agway

 
Provide Stable Rations
"Using fermentation analysis helps us eliminate the bumps in the road of nutrition," says New York producer Noble. So, instead of waiting for a blowup to occur, this tool helps you or your nutritionist prevent the problems in the first place.

From using fermentation analysis Corbett has learned that when the lactic acid of corn silage is less than 50 percent of the total acid profile, he needs to reduce the amount of corn silage fed and increase the amount of haylage in order to keep intakes stable. (His preferred level of lactic acid content is 70 percent or higher of the total acid content.)

In addition, knowing the acid profile helps you judge susceptibility to heating and secondary growth of yeasts and molds while in storage, says Brian Perkins, technical services specialist for Monsanto Dairy Business in Twin Falls, Idaho. The lower the total acid content of the ensiled forage, the greater the chance for secondary yeast and mold growth and subsequent heating to occur while in storage or at the bunk.

Improve Your Silage Production
"If you want to get your cows to produce more milk, you've got to look for ways to improve dry matter intake," says Noble, whose cows generally consume about 54 pounds of dry matter and produce about 75 pounds of milk per day. "Fermentation analysis has taught us a lot about how to make better silage, which boosts dry matter intake," he says.

At Southview Dairy, those changes have included harvesting haylage and corn silage a bit drier, and covering all of the bunkers with plastic in order to improve fermentation results.

Nutritionists and veterinarians who have used fermentation analysis agree that the test results can be an eye-opening experience for their clients. After seeing why the cows are not eating as well as expected or why production is down -- or even how to improve silage production -- the response is generally "wow." (See the table below -- "How fermentation analysis works.")

How Fermentation Analysis Works
Researchers have used fermentation analysis for years. However, it wasn't until recently that these evaluations were made commercially-available, says Ralph Ward, Cumberland Valley Analytical.  Fermentation analysis provides a look back at what happened during fermentation of the forage. With that information in hand, producers can learn to improve silage production and make better feeding decisions.  Here's how the test works.
1. Collect a silage or haylage sample in the same manner you would for a wet chemistry or NIR analysis. Remove as much air as possible, seal and send to the lab quickly.
2. At the lab, a portion of the sample is placed in a blender. The sample is mixed with distilled water and blended to liquefy it.
3. The liquid portion is what contains the volatile compounds you want to evaluate. The liquid is poured through filter paper and then separated into four parts.
Some of the liquid is placed in a gas chromatograph to determine acetic, propionic and iso-butyric acid content.
Another portion of the liquid is placed in a membrane analyzer to determine lactic acid content.
A third portion of the liquid is placed in the ammonia distiller-titrater which determines ammonia content.
The fourth liquid portion is placed into a pH meter/titrater to determine overall pH and total acid content.
4. From these tests, a report is generated.

"All of my clients for whom we have had fermentation analysis done have since purchased a Koster tester or an accurate gram scale and microwave to do dry matter analysis," says Corbett. Knowing the dry matter content before harvest, not estimating it, is the first step toward improving fermentation and producing better silage.

For Kozlowski, the teachable moment arrived in 1997 when a lot of producers in western New York put their haylage up too wet. Although the nutritional analysis was good, milk production on these herds was lower than expected. Fermentation analysis revealed high acetic acid and high ammonia levels in their first-cut haylages. These two factors led to poor intake, reduced milk production and an increase in fresh cow health problems. Kozlowski gathered analyses from several farms, called all of the producers together for a meeting, and showed them what had gone wrong. The next year, producers harvested alfalfa for haylage at a target dry matter percent of 35 to 40 instead of the average 28 percent to 32 percent dry matter from the year before, and the result was a 3- to 5-pound increase in milk per cow per day.

Give It a Try
Knowing the acid profile of the silage or haylage can help you improve forage production, better match feeds with your cows needs, thus maximizing dry matter intake, increasing milk production, reducing health problems -- and improving your bottom line.

Reprinted with permission of Dairy Herd Management.